Add railing parametric edit + schematic preview

Port gizmos-8088's railing gizmo block to v0.8.0: - _RailingEditMixin (PathPreservingEditMixin specialisation) + EnableEditingRailing / CancelEditingRailing / FinishEditingRailing edit triad - CycleRailingType (2-value type cycler) + ToggleRailingUseManualSupports one-shot + EditRailingTerminalType - FlipRailingPathOrder + EnableEditingRailingPath / CancelEditingRailingPath / FinishEditingRailingPath path-edit operators (mutually exclusive with the schematic frame) - GizmoRailingSchematic (BaseSchematicGizmoGroup specialisation) — axonometric schematic frame with per-attribute dimension gizmos for FRAMELESS_PANEL + WALL_MOUNTED_HANDRAIL railing types; hover-on-attr highlights the schematic edges tagged with the matching feature Tests: test_railing_lifecycle.py (280 LOC) + test_railing_schematic.py (272 LOC). Drops the per-feature GizmoPreferences{Door,Window,Stair,Wall,Roof, Railing} PropertyGroups that the source commit added to bim/ui.py — that finer-grained per-attribute toggle model was deliberately collapsed to flat per-feature bools in the PR5b prefs sweep, and GizmoRailingSchematic gates on the flat ``prefs.gizmos.railing`` bool via ``gizmo_pref_name`` so no functionality is lost. Generated with the assistance of an AI coding tool.
2026-09-12 06:32:09 +00:00 · 2026-06-10 20:40:33 +02:00
parent 251157f8d4
commit d1d1e1d4a2
4 changed files with 1266 additions and 10 deletions
@@ -0,0 +1,280 @@
+# Bonsai - OpenBIM Blender Add-on
+# Copyright (C) 2026
+#
+# This file is part of Bonsai.
+#
+# Bonsai is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# Bonsai is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with Bonsai.  If not, see <http://www.gnu.org/licenses/>.
+#
+# This file was generated with the assistance of an AI coding tool.
+
+"""Unit coverage for the ``_RailingEditMixin`` lifecycle overrides.
+
+The generic ``PathPreservingEditMixin`` lifecycle is tested in
+``test_parametric_lifecycle.py``. This file pins the **railing-specific
+overrides** that subclass it:
+
+- ``_RailingEditMixin._finish_one`` short-circuit: when the draft equals
+  the stored pset, ``_update_pset`` and ``_update_modifier_ifc_data`` are
+  skipped so an Enable → Finish-without-changes cycle creates no new
+  ``IfcShapeRepresentation``.
+- ``_RailingEditMixin._cancel_one`` short-circuit: same logic guards the
+  expensive ``bonsai.core.geometry.switch_representation`` call (which
+  re-tessellates the swept-disk solid) when nothing actually changed.
+- ``_RailingEditMixin._cancel_one`` WALL_MOUNTED_HANDRAIL branch: when
+  changes WERE made, the cancel reloads the IFC body via
+  ``switch_representation`` instead of running ``update_modifier_bmesh``
+  (which would leave the low-poly cylinder-segment preview on screen).
+"""
+
+from unittest import mock
+
+import pytest
+
+from test.bim.conftest import _FakePropsBase
+from test.bim.conftest import make_lifecycle_obj as _make_obj
+
+pytestmark = pytest.mark.model
+
+
+# ---------------------------------------------------------------------------
+# Helpers
+# ---------------------------------------------------------------------------
+
+
+class _FakeRailingProps(_FakePropsBase):
+    """Stand-in for ``BIMRailingProperties`` — adds ``railing_type`` on top of
+    the shared parametric-edit contract. Starts in ``is_editing=True`` because
+    the railing-specific overrides under test only fire on Finish / Cancel,
+    not on Enable."""
+
+    def __init__(self, railing_type: str = "WALL_MOUNTED_HANDRAIL", general: dict | None = None):
+        super().__init__(general=general if general is not None else {"railing_type": railing_type, "height": 1.0})
+        self.railing_type = railing_type
+        self.is_editing = True
+
+
+@pytest.fixture
+def patched_railing():
+    """Patch the railing module's external references for unit testing.
+
+    ``_RailingEditMixin`` calls ``tool.Model.get_modeling_bbim_pset_data``,
+    ``tool.Ifc.get_entity``, ``ifcopenshell.util.representation.get_representation``,
+    and ``bonsai.core.geometry.switch_representation`` — each looked up
+    through the railing module's own bindings, so we patch them there.
+
+    Uses ``mock.patch.object`` with a direct module reference rather than
+    the dotted-string form: ``mock.patch("bonsai.bim.module.model.railing.bonsai")``
+    needs ``pkgutil.resolve_name`` to traverse ``bonsai → bim → module → …``,
+    which fails at the ``bonsai.bim`` step until that subpackage has been
+    imported elsewhere. The direct-object form sidesteps the resolution.
+
+    Returns a dict for tests to seed return values and assert call sites.
+    """
+    from bonsai.bim.module.model import railing
+
+    with (
+        mock.patch.object(railing, "tool") as mock_tool,
+        mock.patch.object(railing, "ifcopenshell") as mock_ifc,
+        mock.patch.object(railing, "bonsai") as mock_bonsai,
+    ):
+        # _resolve will be overridden on the test subclass below so the
+        # parametric_lifecycle.tool patch isn't needed.
+        mock_tool.Ifc.get_entity.return_value = mock.Mock(name="entity")
+        yield {"tool": mock_tool, "ifcopenshell": mock_ifc, "bonsai": mock_bonsai}
+
+
+def _railing_test_subclass(props):
+    """Build a ``_RailingEditMixin`` subclass that bypasses ``_resolve``.
+
+    The base ``_resolve`` reads ``tool.Ifc.get_entity`` from
+    ``parametric_lifecycle.tool`` (a separate import from the railing
+    module's ``tool``). Overriding it here keeps the test patches local
+    to the railing module and the hook closures local to the test."""
+    from bonsai.bim.module.model.railing import _RailingEditMixin
+
+    test_element = mock.Mock(name="ifc_element")
+
+    class _TestRailingMixin(_RailingEditMixin):
+        pset_updates: mock.MagicMock = mock.MagicMock(name="_update_pset")
+        ifc_data_updates: mock.MagicMock = mock.MagicMock(name="_update_modifier_ifc_data")
+        bmesh_updates: mock.MagicMock = mock.MagicMock(name="_update_modifier_bmesh")
+
+        @classmethod
+        def _resolve(cls, obj):
+            return test_element, props
+
+        @classmethod
+        def _update_pset(cls, element, data):
+            cls.pset_updates(element, data)
+
+        @classmethod
+        def _update_modifier_ifc_data(cls, obj, context):
+            cls.ifc_data_updates(obj, context)
+
+        @classmethod
+        def _update_modifier_bmesh(cls, obj, context):
+            cls.bmesh_updates(obj, context)
+
+        # The base _post_load_data JSON-serialises path_data; bypass that
+        # here so the round-trip stays a plain dict and tests can compare
+        # by reference / equality without re-parsing.
+        @classmethod
+        def _post_load_data(cls, data):
+            return dict(data)
+
+    return _TestRailingMixin, test_element
+
+
+# ---------------------------------------------------------------------------
+# _RailingEditMixin._finish_one
+# ---------------------------------------------------------------------------
+
+
+def test_finish_one_short_circuits_when_draft_matches_stored(patched_railing):
+    """Enable → Finish without any property edit must NOT write to IFC.
+
+    Without this, every "open Edit, click Validate immediately" cycle
+    would create a fresh ``IfcShapeRepresentation``, pollute the file's
+    representation list, and burn an undo entry — the user-visible
+    regression that motivated the short-circuit.
+    """
+    stored = {"railing_type": "WALL_MOUNTED_HANDRAIL", "height": 1.0}
+    props = _FakeRailingProps(general=dict(stored))
+    obj = _make_obj(props)
+    patched_railing["tool"].Model.get_modeling_bbim_pset_data.return_value = {
+        "data_dict": {**stored, "path_data": {"verts": [], "edges": []}},
+    }
+
+    cls, _element = _railing_test_subclass(props)
+    cls._finish_one(obj, mock.Mock(name="context"))
+
+    assert props.is_editing is False, "is_editing must still flip even on no-op"
+    cls.pset_updates.assert_not_called()
+    cls.ifc_data_updates.assert_not_called()
+
+
+def test_finish_one_writes_when_draft_differs(patched_railing):
+    """The complement of the short-circuit: a real property change must
+    flow through to ``_update_pset`` + ``_update_modifier_ifc_data``."""
+    stored = {"railing_type": "WALL_MOUNTED_HANDRAIL", "height": 1.0}
+    # Draft height differs: simulating a user edit.
+    props = _FakeRailingProps(general={"railing_type": "WALL_MOUNTED_HANDRAIL", "height": 1.5})
+    obj = _make_obj(props)
+    patched_railing["tool"].Model.get_modeling_bbim_pset_data.return_value = {
+        "data_dict": {**stored, "path_data": {"verts": [], "edges": []}},
+    }
+
+    cls, element = _railing_test_subclass(props)
+    cls._finish_one(obj, mock.Mock(name="context"))
+
+    assert props.is_editing is False
+    cls.pset_updates.assert_called_once()
+    # The pset must receive the DRAFT data, not the stored data — that's the
+    # whole point of Finish committing the user's edits.
+    written = cls.pset_updates.call_args[0][1]
+    assert written["height"] == 1.5
+    cls.ifc_data_updates.assert_called_once_with(obj, mock.ANY)
+
+
+# ---------------------------------------------------------------------------
+# _RailingEditMixin._cancel_one
+# ---------------------------------------------------------------------------
+
+
+def test_cancel_one_short_circuits_when_draft_matches_stored(patched_railing):
+    """Cancel-without-changes is asymmetrically expensive without this guard:
+    ``switch_representation`` re-tessellates the IfcSweptDiskSolid and is
+    visibly slow on a long handrail. When nothing changed, the mesh on
+    screen is still the committed IFC representation (the preview only
+    builds on a property change) — skip the reload entirely.
+    """
+    stored = {"railing_type": "WALL_MOUNTED_HANDRAIL", "height": 1.0}
+    props = _FakeRailingProps(general=dict(stored))
+    obj = _make_obj(props)
+    patched_railing["tool"].Model.get_modeling_bbim_pset_data.return_value = {
+        "data_dict": {**stored, "path_data": {"verts": [], "edges": []}},
+    }
+
+    cls, _element = _railing_test_subclass(props)
+    cls._cancel_one(obj, mock.Mock(name="context"))
+
+    assert props.is_editing is False
+    patched_railing["bonsai"].core.geometry.switch_representation.assert_not_called()
+    cls.bmesh_updates.assert_not_called()
+
+
+def test_cancel_one_wall_mounted_handrail_switches_representation(patched_railing):
+    """Cancel after a real edit on a WALL_MOUNTED_HANDRAIL must reload the
+    committed Body representation (high-poly, IFC-derived) rather than
+    re-running the low-poly bmesh preview — that preview is a viewport-only
+    approximation and would persist visibly after Cancel without this.
+    """
+    stored = {"railing_type": "WALL_MOUNTED_HANDRAIL", "height": 1.0}
+    # Differs → not a no-op → cancel must take the real branch.
+    props = _FakeRailingProps(
+        railing_type="WALL_MOUNTED_HANDRAIL",
+        general={"railing_type": "WALL_MOUNTED_HANDRAIL", "height": 1.5},
+    )
+    obj = _make_obj(props)
+    patched_railing["tool"].Model.get_modeling_bbim_pset_data.return_value = {
+        "data_dict": {**stored, "path_data": {"verts": [], "edges": []}},
+    }
+    body_repr = mock.Mock(name="body_representation")
+    patched_railing["ifcopenshell"].util.representation.get_representation.return_value = body_repr
+
+    cls, _element = _railing_test_subclass(props)
+    cls._cancel_one(obj, mock.Mock(name="context"))
+
+    assert props.is_editing is False
+    # Must call switch_representation with the Body representation; must NOT
+    # call _update_modifier_bmesh (that's the FRAMELESS branch).
+    patched_railing["bonsai"].core.geometry.switch_representation.assert_called_once()
+    kwargs = patched_railing["bonsai"].core.geometry.switch_representation.call_args.kwargs
+    assert kwargs["obj"] is obj
+    assert kwargs["representation"] is body_repr
+    cls.bmesh_updates.assert_not_called()
+
+
+def test_cancel_one_frameless_panel_runs_bmesh_preview(patched_railing):
+    """FRAMELESS_PANEL's bmesh IS the canonical mesh — there's no IFC
+    swept-disk solid to reload. Cancel must run the bmesh rebuild instead
+    of switch_representation, which would no-op or worse."""
+    stored = {"railing_type": "FRAMELESS_PANEL", "height": 1.0, "thickness": 0.05}
+    props = _FakeRailingProps(
+        railing_type="FRAMELESS_PANEL",
+        general={"railing_type": "FRAMELESS_PANEL", "height": 1.0, "thickness": 0.08},
+    )
+    obj = _make_obj(props)
+    patched_railing["tool"].Model.get_modeling_bbim_pset_data.return_value = {
+        "data_dict": {**stored, "path_data": {"verts": [], "edges": []}},
+    }
+
+    cls, _element = _railing_test_subclass(props)
+    cls._cancel_one(obj, mock.Mock(name="context"))
+
+    assert props.is_editing is False
+    cls.bmesh_updates.assert_called_once_with(obj, mock.ANY)
+    patched_railing["bonsai"].core.geometry.switch_representation.assert_not_called()
+
+
+# ---------------------------------------------------------------------------
+# _get_railing_path_anchor: tests removed.
+#
+# The schematic-redesign branch replaced ``GizmoRailingEdition`` with
+# ``GizmoRailingSchematic``, which anchors via the schematic frame rather
+# than the polyline's first vertex. ``_get_railing_path_anchor`` was the
+# helper for the old anchor strategy and has been deleted along with the
+# old gizmo group. If schematic-mode gains a similar path-derived helper,
+# new tests should land here.
+# ---------------------------------------------------------------------------
@@ -0,0 +1,272 @@
+# Bonsai - OpenBIM Blender Add-on
+# Copyright (C) 2026
+#
+# This file is part of Bonsai.
+#
+# Bonsai is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# Bonsai is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with Bonsai.  If not, see <http://www.gnu.org/licenses/>.
+#
+# This file was generated with the assistance of an AI coding tool.
+
+import types
+from types import SimpleNamespace
+
+import bmesh
+import bpy
+import pytest
+
+from bonsai import tool
+from bonsai.bim.module.drawing.gizmos import (
+    BaseSchematicGizmoGroup,
+    DimensionGizmoConfig,
+)
+from bonsai.bim.module.model.railing import GizmoRailingSchematic
+
+pytestmark = pytest.mark.railing
+
+
+@pytest.fixture(autouse=True)
+def _require_real_bpy():
+    """Skip the file when ``bpy`` is mocked or absent.
+
+    Without this guard, mis-routed test runs (e.g. ``pytest test/bim/...``
+    invoked outside Blender) crash at module-collection time on the chain of
+    ``bonsai.tool`` imports below, instead of producing a clean ``skipped``.
+    """
+    if not isinstance(bpy, types.ModuleType) or hasattr(bpy, "_mock_name"):
+        pytest.skip("requires real Blender (bpy is mocked or absent)")
+
+
+# ── Class shape ──────────────────────────────────────────────────────────────
+
+
+def test_railing_schematic_inherits_base():
+    """GizmoRailingSchematic plugs into the schematic framework, not the
+    in-place dimension framework. If a future refactor breaks this lineage
+    the schematic-specific machinery (sliders, draw handler) silently goes
+    dormant."""
+    assert issubclass(GizmoRailingSchematic, BaseSchematicGizmoGroup)
+
+
+def test_railing_schematic_bl_idname_preserved():
+    """``OBJECT_GGT_bim_railing_edition`` is the user-facing identifier and
+    is referenced by keymaps and persistence. Preserve it across the class
+    rename — see the migration note in the class docstring."""
+    assert GizmoRailingSchematic.bl_idname == "OBJECT_GGT_bim_railing_edition"
+
+
+def test_railing_schematic_props_getter_pairing():
+    """``gizmo_pref_name = "railing"`` and ``props_getter = tool.Model.get_railing_props``
+    are the pairing test_parametric_registry depends on. If either drifts,
+    the addon-preferences gizmo toggle silently stops controlling this group."""
+    assert GizmoRailingSchematic.gizmo_pref_name == "railing"
+    assert GizmoRailingSchematic.props_getter == tool.Model.get_railing_props
+
+
+def test_railing_schematic_disables_in_place_dimension_props():
+    """The schematic owns the value-input surface — no in-place dimensions on the actual geometry."""
+    assert GizmoRailingSchematic.dimension_gizmo_props == []
+
+
+# ── Dimension configuration ─────────────────────────────────────────────────
+
+
+def test_railing_schematic_has_six_dimensions():
+    """One dimension per parametric property — three for each railing_type."""
+    assert len(GizmoRailingSchematic.schematic_dimension_props) == 6
+
+
+def test_railing_schematic_dimension_attr_names_complete():
+    """The six bound attributes match the parametric properties that
+    ``update_railing_modifier_bmesh`` reads when regenerating the live preview."""
+    attr_names = {c.attr_name for c in GizmoRailingSchematic.schematic_dimension_props}
+    assert attr_names == {
+        "height",
+        "thickness",
+        "spacing",
+        "railing_diameter",
+        "clear_width",
+        "support_spacing",
+    }
+
+
+def test_railing_schematic_dimensions_are_dimension_configs():
+    """The dimension-line aesthetic depends on ``DimensionGizmoConfig`` (with
+    arrows + label), not the abstract slider widget."""
+    for config in GizmoRailingSchematic.schematic_dimension_props:
+        assert isinstance(config, DimensionGizmoConfig)
+
+
+def test_railing_schematic_dimensions_have_text_formatters():
+    """Each dimension must format the label from the actual property value,
+    not from the visually-scaled value the gizmo's getter returns. Without a
+    formatter the label would show the schematic-scaled length, which is
+    meaningless to the user."""
+    for config in GizmoRailingSchematic.schematic_dimension_props:
+        assert config.text_formatter is not None, f"{config.attr_name} missing text_formatter"
+
+
+@pytest.mark.parametrize(
+    "attr_name,railing_type,expected",
+    [
+        ("height", "FRAMELESS_PANEL", True),
+        ("height", "WALL_MOUNTED_HANDRAIL", False),
+        ("thickness", "FRAMELESS_PANEL", True),
+        ("spacing", "FRAMELESS_PANEL", True),
+        ("railing_diameter", "WALL_MOUNTED_HANDRAIL", True),
+        ("railing_diameter", "FRAMELESS_PANEL", False),
+        ("clear_width", "WALL_MOUNTED_HANDRAIL", True),
+    ],
+)
+def test_railing_schematic_dimension_visibility_gated_by_railing_type(attr_name, railing_type, expected):
+    """The two railing types are mutually exclusive — height/thickness/spacing
+    belong to FRAMELESS_PANEL; railing_diameter/clear_width/support_spacing
+    belong to WALL_MOUNTED_HANDRAIL. The visibility lambdas enforce that."""
+    config = next(c for c in GizmoRailingSchematic.schematic_dimension_props if c.attr_name == attr_name)
+    props = SimpleNamespace(railing_type=railing_type, use_manual_supports=False)
+    assert config.visibility_condition(props) is expected
+
+
+def test_railing_schematic_support_spacing_hidden_for_manual_supports():
+    """``support_spacing`` only drives auto-positioned supports — when the
+    user has switched to manual supports the dimension should disappear."""
+    config = next(c for c in GizmoRailingSchematic.schematic_dimension_props if c.attr_name == "support_spacing")
+    auto = SimpleNamespace(railing_type="WALL_MOUNTED_HANDRAIL", use_manual_supports=False)
+    manual = SimpleNamespace(railing_type="WALL_MOUNTED_HANDRAIL", use_manual_supports=True)
+    assert config.visibility_condition(auto) is True
+    assert config.visibility_condition(manual) is False
+
+
+# ── Fixed-length tag rendering ─────────────────────────────────────────────
+
+
+def test_schematic_dim_visible_length_is_constant():
+    """Every schematic dimension tag renders at the same width — the bar is a
+    UI affordance, not a proportional measurement. The constant ratio keeps
+    tiny (5 mm thickness) and huge (5 m height) values equally clickable; the
+    real value lives in the dimension label.
+
+    Regression guard: if value-proportional scaling is reintroduced, this
+    contract breaks silently — small dimensions start collapsing into stacked
+    arrows again.
+    """
+    cls = GizmoRailingSchematic
+    ratio = cls.SCHEMATIC_DIM_VISIBLE_LENGTH_RATIO
+    assert ratio > 0
+    assert ratio <= 1.0  # bar must fit within the schematic box
+
+
+def test_schematic_no_compute_schematic_scale_override():
+    """The constant-length design has no need for a scale factor. If a
+    subclass redefines ``_compute_schematic_scale``, it indicates the
+    scale-based proportional sizing was reintroduced — which is the design
+    we deliberately stepped away from."""
+    assert "_compute_schematic_scale" not in GizmoRailingSchematic.__dict__
+
+
+# ── Path-edit guard ─────────────────────────────────────────────────────────
+
+
+def test_update_editing_gizmos_override_defined_on_subclass():
+    """``GizmoRailingSchematic`` must own the override that hides the pen
+    icon during path-edit. The parent's version shows the pen whenever
+    ``is_editing`` is False, which includes path-edit; that would let the
+    user open two editing modes at once."""
+    assert "update_editing_gizmos" in GizmoRailingSchematic.__dict__
+
+
+# ── Schematic mesh building ─────────────────────────────────────────────────
+
+
+def test_build_schematic_mesh_frameless_panel_returns_bmesh_with_edges():
+    """FRAMELESS_PANEL renders as two separated wireframe boxes — 8 corners
+    per box × 2 = 16 verts; 12 edges per box × 2 = 24 edges. The visible
+    gap between the two boxes is the "spacing" semantic made literal.
+
+    The mesh proportions are fixed (independent of property values) so the
+    dimension gizmos can anchor to known feature positions; the property
+    values are shown through dimension labels, not the mesh size."""
+    props = SimpleNamespace(
+        railing_type="FRAMELESS_PANEL",
+        height=1.0,
+        thickness=0.05,
+        spacing=0.5,
+    )
+    bm = GizmoRailingSchematic.build_schematic_mesh(props)
+    try:
+        assert isinstance(bm, bmesh.types.BMesh)
+        assert len(bm.verts) == 16
+        assert len(bm.edges) == 24
+    finally:
+        bm.free()
+
+
+def test_build_schematic_mesh_wall_mounted_handrail_returns_bmesh_with_edges():
+    """WALL_MOUNTED_HANDRAIL renders as three visual elements:
+
+    - **Wall outline** — 4 corner verts, 4 edges (rectangle at z=0).
+    - **Hex tube** — 12 verts (6 per ring × 2 ends), 18 edges
+      (6 left ring + 6 right ring + 6 axial).
+    - **L-brackets** at each rail end — 3 verts per bracket (rail centre,
+      corner, wall attach) × 2 brackets = 6 verts; 2 edges per bracket
+      (rail→corner, corner→wall) × 2 = 4 edges.
+
+    Total: 22 verts, 26 edges.
+    """
+    props = SimpleNamespace(
+        railing_type="WALL_MOUNTED_HANDRAIL",
+        railing_diameter=0.05,
+        clear_width=0.04,
+        support_spacing=1.0,
+    )
+    bm = GizmoRailingSchematic.build_schematic_mesh(props)
+    try:
+        assert isinstance(bm, bmesh.types.BMesh)
+        assert len(bm.verts) == 22
+        assert len(bm.edges) == 26
+    finally:
+        bm.free()
+
+
+def test_build_schematic_mesh_proportions_independent_of_props():
+    """The mesh uses fixed proportions so dimension gizmo anchor points stay
+    aligned with the geometry — extreme prop ratios don't change the mesh."""
+    small = SimpleNamespace(railing_type="FRAMELESS_PANEL", height=0.01, thickness=0.005, spacing=0.05)
+    large = SimpleNamespace(railing_type="FRAMELESS_PANEL", height=10.0, thickness=0.5, spacing=2.0)
+    bm_small = GizmoRailingSchematic.build_schematic_mesh(small)
+    bm_large = GizmoRailingSchematic.build_schematic_mesh(large)
+    try:
+        # Same vert count regardless of prop magnitude.
+        assert len(bm_small.verts) == len(bm_large.verts)
+        # Same bounding box in each axis (within floating-point noise).
+        for axis in range(3):
+            small_coords = [v.co[axis] for v in bm_small.verts]
+            large_coords = [v.co[axis] for v in bm_large.verts]
+            assert min(small_coords) == pytest.approx(min(large_coords))
+            assert max(small_coords) == pytest.approx(max(large_coords))
+    finally:
+        bm_small.free()
+        bm_large.free()
+
+
+def test_build_schematic_mesh_panel_top_matches_height_frac():
+    """The panel's top edge sits at exactly ``SCHEMATIC_MESH_HEIGHT_FRAC``,
+    which is also where the ``thickness`` dimension anchors above the box.
+    If this drifts, the dimension labels float disconnected from the mesh."""
+    props = SimpleNamespace(railing_type="FRAMELESS_PANEL", height=1.0, thickness=0.05, spacing=0.3)
+    bm = GizmoRailingSchematic.build_schematic_mesh(props)
+    try:
+        max_y = max(v.co.y for v in bm.verts)
+        assert max_y == pytest.approx(GizmoRailingSchematic.SCHEMATIC_MESH_HEIGHT_FRAC)
+    finally:
+        bm.free()